1. Field of the Invention
The present invention relates to a camera having an aperture portion an opening shape of which can be changed.
2. Related Background Art
As an example of the camera capable of taking a photograph with changeable shape of opening in an aperture portion for permitting photographic light to pass therethrough, there is a camera switchable between a normal image plane size and a panoramic image plane size, as proposed in Japanese Laid-open Patent Application No. 3-238439 and No. 3-238440. The camera is provided with a pair of light shielding plates near an aperture having an opening for permitting photographic light of normal image plane size to pass therethrough. Each of the shielding plates has an edge parallel to a facing frame edge of the aperture. Operating an operation member provided on the camera, each of the shielding plates is moved toward the other frame edge of the aperture, whereby the opening of the aperture may be switched between the normal image plane size and the elongated panoramic size.
However, if the operation of the operation member was incomplete, or if the movement of the light shielding plates was interrupted, for example, by intrusion of dust into an operating portion of the shielding plates, the shielding plates would be stopped halfway between the normal photographic position and the panoramic photographic position. Such a state would cause a problem of leaving an unexposed portion on the film if a photographer intended to take a normal photograph. Also, if the photographer intended to take a panoramic photograph, the problem of incorrect exposure would be caused, which results in failure in obtaining a photograph of correct panoramic size on the film. Further, the above state would cause a trouble of improper operation during automatic operation such as the mode change of automatic exposure, the autozooming of a zoom lens, and the mode change of photometry in the normal photographic state or in the panoramic photographic state.
The operational state of shielding plates could be checked while opening a back lid of camera body, but cannot be checked when a film is loaded.